Realizing excellent strength-ductility synergy in ultrafine-grained medium W content composites reinforced with multiple strengthening mechanisms

In this article, ultrafine-grained W-Ni-Fe composite with medium W content was successfully fabricated via methods composed of spray-drying, two-stage reduction and low-temperature sintering. It is noticed that the variation of matrix phase fractional volume was effective to tailor the microstructure, mechanical performance and deformation behavior. The microstructure of the medium heavy alloy (MHA) underwent the obvious change from traditional coarsen W grains (>40 mu m) to those with sizes of only 3.5 mu m, accompanied by a large number of nanosized W precipitate. The two main fracture types of MHA are the W cleavage fracture and matrix phase ductile rupture. The additions of Mo and La2O3 revealed three kinds of strengthening effects, including fine-grained, solid-solution and dispersion strengthening. Experimental results showed that a significant enhancement in tensile properties (similar to 972.5 MPa and 26.5%) were benefitted from the cooperation of multiple strengthening and plasticized mechanisms, and the detailed effects of deformed twinning and precipitation strengthening were analyzed. The current findings demonstrated that MHA possessed an outstanding combination of strength and ductility and was a promising alternative to conventional tungsten heavy alloys (WHAs) for a more extensive range of applications.